How would I describe the hybrid orbital formed by 'mixing' one 'd', one 's' and two 'p' orbitals?

I know the shapes of the individual orbitals but I don't know how they 'mix'.

"Mixing" is actually a pseudo-mathematical construct. In actuality, the orbitals would be calculated from the Schrödinger equation. However, since solving that was hard for the hydrogen atoms, it gets down to being nearly impossible (in general) for other molecules. Therefore, theorists decided that they could take the hydrogen orbitals and "hybridize" them to get the mixed orbitals of other species (especially carbon).

check out these links.

Orbital hybridisation - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Hybridized_orbital)

Atomic Orbital - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Atomic_orbital)

Molecular orbital theory - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Molecular_orbital_theory)

As to what a sp2d orbital looks like, check out this link:

http://csi.chemie.tu-darmstadt.de/ak/immel/script/redirect.cgi?filename=http://csi.chemie.tu-darmstadt.de/ak/immel/tutorials/orbitals/hybrid/3d1-4sp2.html

As always your answers are to the point and I appreciate the speed with which you send them!

As to what a sp2d orbital looks like, check out this link:

PD Dr. Stefan Immel (http://csi.chemie.tu-darmstadt.de/ak/immel/script/redirect.cgi?filename=http://csi.chemie.tu-darmstadt.de/ak/immel/tutorials/orbitals/hybrid/3d1-4sp2.html)

This one is like a kidney, lol!

Thanks for the link Perito! I only know about the sp1, sp2 and sp3 hybridizations up to now from the organic chemistry. :)